i reckon this is clearly intended for non-technical business/sales people. from an software/systems engineering perspective i feel that one of the primary benefits of email is its async behaviour.

unlike IRC/IM/video/telephone/face-to-face interactions, which happen in realtime, email provides an opportunity for reflecting on conversations and responses, while also allowing people in diverse geographic areas to take part in the natural flow of a conversation.

couple this with the fact that pretty much anyone can run a mail server and communicate with any other person on the internet - i am not sure how abandoning email communication for closed systems like yammer/facebook for near-time communication would be a net positive.

having said that - adding these tools to your suite of communication formats is clearly a good thing.